1. Field of the Invention
The invention relates to a communication system, a communication method, and a controller. More particularly, the invention relates to a communication system, a communication method, and a controller that check whether a mobile device carried by a user of a vehicle is in a vehicle cabin (hereinafter also simply referred to as “in the vehicle”) via wireless communication between an onboard device and the mobile device, when a door of the vehicle has changed from being open to being closed while the power is on.
2. Description of Related Art
A vehicle control system that allows an engine to start or locks/unlocks a vehicle door via wireless communication between an onboard device and a mobile device carried by a user of a vehicle is known (see Japanese Patent Application Publication No. 2006-104663 (JP 2006-104663 A), for example). In this vehicle control system, in order to prevent the mobile device from being taken out of the vehicle, a vehicle interior check to check whether the mobile device is in the vehicle is performed via wireless communication between the onboard device and the mobile device when a vehicle door is opened or closed.
The vehicle interior check via wireless communication between the onboard device and the mobile device may be impeded by electromagnetic noise generated by a power harness or onboard electrical equipment. If this happens, the vehicle interior check will not be able to be performed properly, and as a result, it may be erroneously determined that the mobile device is not in the vehicle when in fact the mobile device is actually in the vehicle, and an alarm may consequently be issued.
Therefore, in order to avoid this happening, in the vehicle control system described above, when electromagnetic noise of a predetermined level or higher is detected, an alarm is issued to notify a vehicle occupant that this noise has been detected.
However, with the vehicle control system according to JP 2006-104663 A described above, only an alarm is issued when noise from onboard electrical equipment or the like is detected, so wireless communication between the onboard device and the mobile device (i.e., the vehicle interior check) may continue to be impeded by this noise. Therefore, it is difficult to properly perform a vehicle interior check when a vehicle door is opened or closed.
Here, in order to eliminate the effect of noise and detect that the mobile device is in the vehicle cabin by the vehicle interior check, if there is a discrepancy in the vehicle interior check via wireless communication between the onboard device and the mobile device, it is conceivable to perform the check again in a similar manner via wireless communication between the onboard device and the mobile device (hereinafter, this will simply be referred to as a “recheck”).
However, after there has been a discrepancy in the vehicle interior check via wireless communication between the onboard device and the mobile device, the timing of an alarm based on this discrepancy in the check will be increasingly delayed the greater the maximum number of times that a recheck is allowed (i.e., the greater the maximum value of the number of rechecks) is. That is, if the number of rechecks is too large, the alarm to notify a user of the vehicle that the mobile device has been taken out of the vehicle will not be able to be issued quickly. On the other hand, by lowering the maximum value of the number of rechecks, a delay in the alarm timing based on the vehicle interior check discrepancy is able to be reduced, so an alarm indicating that the mobile device has been taken out of the vehicle is able to be issued quickly. However, even if noise is not generated frequently, there are fewer times (i.e., opportunities) when the check will not be affected by this noise when the check is performed, so it is possible that the result of the vehicle interior check may not be positive (check OK) even once, even if the mobile device is in the vehicle cabin. That is, if the number of rechecks is too few, the likelihood of an alarm indicating that the mobile device has been taken out of the vehicle being erroneously issued increases.
The noise may be noise from ignition of an engine or noise from a motor of a vehicle wiper or the like. The way in which the noise is generated, and the level of the noise, differ depending on the noise generating source. Therefore, if the number of rechecks is uniformly set, then depending on the noise generating source, there may end up being a delay in the alarm timing based on a vehicle interior check discrepancy, or an alarm indicating that the mobile device has been taken out of the vehicle may end up being erroneously issued.